Downhole sealing assembly

ABSTRACT

A sealing assembly for sealing an annulus in a downhole application including a sealing ring and a deflecting ring axially aligned between axially opposed mesh back-ups, each of the sealing ring and the deflecting ring defining a first ramped end, the first ramped ends facing each other such that an axial set force applied to the deflecting ring deflects the sealing ring radially outward forcing the sealing ring into a side-by-side arrangement with the deflecting ring to fill and seal the annulus.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from U.S. Provisional App. No.61/791,983 filed Mar. 15, 2013, the entirety of which is incorporated byreference herein.

TECHNICAL FIELD AND BACKGROUND OF THE INVENTION

The present invention relates generally to sealing assemblies used inthe oil and gas industry, and more particularly, to expandable downholesealing assemblies in which an axial setting force is applied toradially compress and self-energize an expanding element such thatstored radial forces in the expanding element effect and maintain a sealthereafter.

Downhole packers are well known in the oil and gas industry for sealingan annulus between various weight casings and mandrels at differentunderground locations in an oil well, for example, to exploit differentproduction zones. Conventional downhole packers include multi-elementelastomeric packers (see FIG. 7), packers including a single elastomericelement having metal or mesh back-ups (see FIG. 8), and inflatablepackers. Elastomeric sealing elements are generally restricted for usein applications up to about 450° F., while high temperature and pressureapplications require flexible or expanded graphite.

Packers having elastomeric sealing elements typically require a largeaxial setting force to deform the sealing element radially outward toreach the interior of the casing. Typically, the greater the settingforce the more energy transferred radially outward. Once set, internalstresses within the sealing element work against the packer as lostenergy, thus an axial maintenance force is required to resist theelastomeric memory of the element. As a result, the packer is not“self-energizing,” and will leak at a pressure higher than itsequilibrium internal pressure without any sign of extrusion.

Geothermal packers used in high temperature applications (e.g., up toabout 650° F.) can include braided graphite packing elements orcompressed flexible graphite elements. These packers also require largeaxial setting forces to deform the element to reach the interior of thecasing. One problem associated with the use of flexible graphiteelements is that they are fragile, and thus susceptible to damage whenthe tool is lowered into the well. To protect the flexible graphiteelements from damage during installation, the elements are typicallycovered with an elastomeric shell, which not only increases thecomplexity of the assembly, but also introduces the problems associatedwith elastomeric memory as discussed above.

Inflatable packers utilize air or other fluid injected into anexpandable element to expand the outer shell to reach the interior ofthe casing. In inflatable packers, the inflation pressure must be higherthan the system pressure in order to maintain a positive seal. Thus,like the other conventional packers discussed above, inflatable packersare not self-energizing. Additionally, any axial movement of the packeror the anchoring stop will relax the packer and reduce the sealing forceaccordingly. Further, when the temperature increases after setting, theelement tends to expand, which further deforms the back-up system tocreate more gland volume or room. Further, changes in internal pressureas a result of thermal cycling affect the sealability.

Accordingly, what is needed is a self-energizing packer that overcomesthe disadvantages of prior art assemblies in that the packer isstructurally simple, requires a minimum setting force, obviates the needfor axial maintenance forces, and is suitable for use with elastomeric,thermoplastic and graphitic elements, among other advantages.

BRIEF SUMMARY OF THE INVENTION

In one aspect, a sealing assembly for use in the oil and gas industry isprovided herein and generally includes a sealing ring (i.e., an“expanding element”) and a deflecting ring, wherein an axial settingforce is applied to the deflecting ring to radially deflect and compressthe sealing ring to force the axially aligned rings into an arrangementin which the sealing ring is radially outside of the deflecting ring. Byradially compressing the sealing ring and causing it to deform, incontrast to conventional packers arrangements in which a sealing elementis axially compressed, stored forces in the sealing ring work to effectand maintain the seal after the setting force is removed.

In another aspect, the sealability of the sealing ring is independent ofthe setting force.

In yet another aspect, the sealing ring is radially compressed betweenthe deflecting element and the interior of the casing when expandeddownhole.

In yet another aspect, the cross-section of the sealing ring increasesin the axial direction and decreases in the radial direction from theunset to the set configurations.

In yet another aspect, the deflecting ring defines a ramped surface atone end thereof facing in the direction of the sealing ring andconfigured for radially displacing the sealing ring upon axial movementof the deflecting ring in the direction of the sealing ring.

In yet another aspect, the deflecting ring defines a first surfacearranged at an angle to the interior wall of the casing, and a secondsurface arranged substantially parallel to the interior wall of thecasing, wherein, upon axial movement of the deflecting ring in thedirection of the sealing ring, at least a portion of the sealing ring isforced passed the first surface and comes to rest over the secondsurface such that a portion of the sealing ring and the deflecting ringoverlap in the axial direction.

In yet another aspect, after the sealing assembly is set (i.e.,“expanded”), the portion of the sealing ring axially overlapping thesecond surface of the deflecting ring is radially compressed to agreater degree than portions of the sealing ring axially overlapping thefirst surface.

In yet another aspect, a portion of the second surface of the deflectingring is recessed radially inward to receive a portion of the deformedsealing ring therein when the sealing ring and the deflecting ringoverlap in the axial direction.

In yet another aspect, the sealing ring is resiliently deformable andassumes a final shape after being set.

In yet another aspect, the sealing ring retains its radially compressedshape and set height after the setting force is removed.

In yet another aspect, the sealing ring is radially compressed such thatits cross-section decreases when set.

In yet another aspect, the sealing ring includes at least one ofelastomeric, thermoplastic, and graphitic materials.

In yet another aspect, axial system pressure in translated into radialforce to self-energize the sealing ring.

In another aspect, the sealing ring is made from PTFE (e.g., virgin orfilled), and is suitable for use in temperature applications from about−50° F. to about 650° F., as well as within harsh chemical environments.

To achieve the forgoing and other aspects and advantages, in a firstembodiment the present invention provides a sealing assembly for sealingan annulus in a downhole application including a sealing ring and adeflecting ring axially aligned between axially opposed mesh back-ups,each of the sealing ring and the deflecting ring defining a first rampedend, the first ramped ends of the sealing ring and the deflecting ringarranged facing each other such that an axial set force applied to thedeflecting ring deflects the sealing ring radially outward forcing thesealing ring into a side-by-side arrangement with the deflecting ring tofill and seal the annulus.

In a further embodiment, the sealing ring is deformable such that whenthe sealing ring is forced radially outward, the sealing ring extendsaxially and compresses radially.

In a further embodiment, the sealing ring has a larger cross-sectionbefore the axial set force is applied than after the axial set force isapplied.

In a further embodiment, the deflecting ring defines a recess along thelength thereof for receiving a portion of the sealing ring therein whenthe sealing assembly is in an expanded configuration.

In a further embodiment, each of the sealing ring and the deflectingring define a second ramp spaced from their respective first ramped end,wherein the second ramp and the ramped end of each of the sealing ringand the deflecting ring are parallel such that when the set force isapplied, the first ramped end of the sealing ring slides against andpasses the second ramp of the deflecting ring, and the first ramped endof the deflecting ring slides against and passes the second ramp of thesealing ring, in the axial direction.

In a further embodiment, the sealing ring defines a second ramped endadjacent the mesh back-up at a 35 degree angle to the longitudinal axisof the sealing assembly, and the deflecting ring defines a second rampedend adjacent the mesh back-up at a 55 degree angle to the longitudinalaxis of the sealing assembly.

In a further embodiment, the sealing assembly includes an o-ringretained against an inner wall of the deflecting ring.

In another embodiment, provided herein is a sealing assembly for sealingan annulus in a downhole application including a sealing ring and adeflecting ring axially aligned between axially spaced mesh back-ups,each of the sealing ring and the deflecting ring defining a first rampedend and a second ramp spaced from the first ramped end, the sealing ringand the deflecting ring arranged such that, when an axial set force isapplied to the deflecting ring, the first ramped end of the deflectingring slides against and passes the second ramp of the sealing ring andthe first ramped end of the sealing ring slides against and passes thesecond ramp of the deflecting ring to deflect the sealing ring radiallyoutward to force the sealing ring into an arrangement in which thesealing ring at least partially overlaps the deflecting ring to seal theannulus.

In a further embodiment, the sealing ring further defines a secondramped end at a 35 degree angle to a longitudinal axis of the sealingassembly, and the deflecting ring defines a second ramped end at a 55degree angle to the longitudinal axis of the sealing assembly.

In yet another embodiment, provided herein is a sealing assembly forsealing an annulus in a downhole application including a deformablesealing ring and a rigid deflecting ring axially aligned between axiallyspaced mesh back-ups, each of the deformable sealing ring and the rigiddeflecting ring defining a first ramped end, the first ramped ends ofthe deformable sealing ring and the rigid deflecting ring arrangedfacing each other such that an axial set force applied to the rigiddeflecting ring deflects the deformable sealing ring radially outwardrelative to a longitudinal axis of the sealing assembly, axiallylengthens the deformable sealing ring, and radially compresses thedeformable sealing ring to force the deformable sealing ring into aside-by-side arrangement with the rigid deflecting ring to fill theannulus.

Additional features, aspects and advantages of the invention will be setforth in the detailed description which follows, and in part will bereadily apparent to those skilled in the art from that description orrecognized by practicing the invention as described herein. It is to beunderstood that both the foregoing general description and the followingdetailed description present various embodiments of the invention, andare intended to provide an overview or framework for understanding thenature and character of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, aspects and advantages of the present invention are betterunderstood when the following detailed description of the invention isread with reference to the accompanying drawings, in which:

FIG. 1 is an axial cross-section of a sealing assembly according to afirst embodiment of the invention;

FIG. 2 is an axial cross-section of a geothermal sealing assemblyaccording to an embodiment of the invention;

FIG. 3 is an axial cross-section of the sealing assembly of FIG. 1 shownexpanded downhole;

FIG. 4 is an axial cross-section of a downhole sealing assembly having arecessed formed in the deflecting element of the assembly, and shownexpanded downhole;

FIG. 5 is a perspective view of another embodiment of a sealingassembly;

FIG. 6 is an axial cross-section of the sealing assembly of FIG. 5;

FIG. 7 is an axial cross-section of a prior art sealing assembly; and

FIG. 8 is an axial cross-section of another prior art sealing assemblyincluding multiple, spaced sealing elements.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described more fully hereinafter withreference to the accompanying drawings in which exemplary embodiments ofthe invention are shown. However, the invention may be embodied in manydifferent forms and should not be construed as limited to therepresentative embodiments set forth herein. The exemplary embodimentsare provided so that this disclosure will be both thorough and complete,and will fully convey the scope of the invention and enable one ofordinary skill in the art to make, use and practice the invention. Likereference numbers refer to like elements throughout the variousdrawings.

Referring to FIG. 1, a first embodiment of a sealing assembly (e.g., a“downhole packer”) suitable for use in downhole applications in the oiland gas industry is shown generally at reference numeral 10. The sealingassembly 10, shown prior to being set (i.e., in an “unexpanded”configuration), generally includes a deflecting ring 12 and a sealingring 14 arranged between (i.e., sandwiched) axially opposed back-upsystems 16. The deflecting ring 12 is positioned on the “stroking” ordynamic side of the assembly 10, and moves with a gauge ring to axiallyexpand the sealing ring 14, as described in detail below. An O-ring 18may be retained in an annular slot along the interior wall of thedeflecting ring 12 that functions to further effect a seal between thedeflecting ring 12 and the outer wall of a cylindrical mandrel (see FIG.3).

The deflecting ring 12 can be made from any suitable material orcombination of materials including, but not limited to, PTFE (filled orvirgin), PPS, PEEK, elastomer, thermoplastic material or metal/alloy.The back-up systems 16 can be made from any material or combination ofmaterials including, but not limited to, Sintermesh™, Unsintermesh™,wire mesh, graphoil with wire mesh, of the like, with the back-upsystems being capable of expanding to close extrusion gaps between thegauge ring and the casing interior. The sealing ring 14, also referredto herein as the “expanding element,” can be made from any material orcombination of materials including, but not limited to, elastomeric,thermoplastic and graphitic materials. The sealing ring 14 may be amachined or molded elastomeric element suitable for use in applicationsup to about 450° F. Applications above about 450° F. may requirethermoplastic PTFE compounds and/or graphitic elements.

The deflecting ring 12 is an annular ring defining a ramped surface 20(i.e., a surface at an angle to the axial direction) at one end thereoffacing in the direction of and in physical contact with a correspondingramped surface 22 of the sealing ring 14. During setting, the rampedsurfaces 20, 22 of the components slide passed one another such that theangular relationship therebetween causes at least a portion of thedeflecting ring 12 to slide beneath at least a portion of the sealingring 14, thereby deflecting at least a portion of the sealing elementradially outward. As used herein, the term “axial” or “axial direction”is intended to mean in the direction along the axis of the well bore,casing, mandrel or sealing element. As used herein, the term “radial,”“radially” or “radial direction” is intended to mean in the directionfrom the center of the well bore, casing, mandrel or sealing elementoutward, or from the circumference of the well bore, casing or sealingelement inward.

The deflecting ring 12 further defines a substantially flat surface 24or “table” adjacent the ramped surface 20, that at least partiallyslides beneath the sealing ring 14 when the sealing assembly 10 is inits expanded configuration. Surface 24 is arranged substantiallyparallel to the axial direction. Referring to FIG. 4, surface 24 mayoptionally include at least one shaped recess 26 positioned along thelength thereof for receiving a portion of the deformed sealing ring 14therein when the packer is expanded. The receipt of a portion of thesealing ring 14 in the recess 26 further resists relative axial movementbetween the sealing ring and the deflecting ring when the packer isexpanded.

Referring to FIGS. 3 and 4, the sealing assembly 10 with and without therecess 26 is shown in the expanded configuration. When the axial setforce is applied, the deflecting ring 12 moves axially in the directionof the sealing ring 14, thus forcing the sealing ring radially outward.As the deflecting ring 12 continues to be forced in the direction of thesealing ring 14, the space constraints between the casing 28 and thedeflecting ring force the deformable sealing ring to radially compressand axially expand to fill the annulus (i.e., “gap”) between thedeflecting ring and the interior wall of the casing. Because the sealingring's starting radial cross-section is greater than the space betweenthe deflecting ring 12 and the interior wall of the casing 28, thesealing ring 14 is radially compressed or “squeezed,” with predeterminedmaximum and minimum compression based on the casing weight tolerance. Atthe same time, the back-up system 16 is activated and expanded until itreaches the interior wall of the casing 28, assuring zero extrusiongaps.

When set, the sealing ring 14 and surface 26 overlap in the axialdirection. In other words, with the sealing assembly is expanded, thesealing ring 14 and the deflecting ring 12 are side-by-side, with thesealing ring 14 radially outward of the deflecting ring 12. The extentof overlap depends upon the starting thickness of the sealing ring 14,the size of the annulus to be filled, the length of the second surface26, etc. Once set, because the sealing ring 12 is radially compressed,the elastic memory of the material wants to return to its originalcross-section (i.e., wants to radially expand). This compressivestrength acts on the deflecting ring 12 and the interior wall of thecasing 28, illustrated by the small force arrows 30, to create a highcontact load on the sealing ring 12, thus providing a “self-energized”seal between the deflecting ring 12 and the interior of the casing 28.

The seal achieved as a result of the radial compression of the sealingring 12 and the O-ring 18 cooperate to achieve a high-pressure sealbetween the interior of the casing 28 and exterior of the mandrel 32.Removing or relaxing the setting force and/or removing the anchoringsystem has no appreciable effect on the seal performance once set.Additionally, the low end of a thermal cycle will not cause anappreciable reduction of the sealing ring's 14 internal stress, andconsistent sealability can be maintained similar to the originalsetting.

Referring to FIG. 2, an embodiment of a geothermal packer for hightemperature applications is shown generally at reference numeral 34.Because of the high temperatures in such applications, the sealing ring14 may be made from thermoplastic PTFE compounds or graphitic elements.In this embodiment, the sealing ring 14 defines a tapered portion 36having a ramped surface that tapers in thickness in the direction of thedeflecting ring 12. In use, when the axial set force is applied, thedeflecting ring 12 moves in the direction of the sealing ring 14,thereby deflecting the sealing ring 14 radially outward, and forcing thesealing ring 14 into the gap between the deflecting ring and theinterior wall of the casing.

When set or “expanded,” the sealing ring 14 and the deflecting ring 12overlap in the axial direction over the length of the tapered portion36. At the same time, the back-up system 16 is activated and expandeduntil it reaches the interior wall of the casing, assuring zeroextrusion gaps. The compressive forces in the sealing ring 14 urgeagainst the deflecting ring 12 and the interior wall of the casing tocreate a high contact load on the sealing ring 14, thus achieving a sealbetween the deflecting ring and the interior wall of the casing. Theback-up requirements in the geothermal packer may be relaxed due to thelower pressure as compared to the embodiment described above.

Referring to FIGS. 5 and 6, another embodiment of a sealing assembly isshown generally at reference numeral 40. The sealing assembly 40, shownin an unexpanded configuration, generally includes an expanding element,a deflecting element, and back-ups at both ends. Specifically, sealingassembly 40 includes a deflecting ring 12 (or “ramping ring”) and asealing ring 14 arranged between axially opposed back-up systems 16. Thedeflecting ring 12 is positioned on the “stroking” or dynamic side ofthe assembly 40, and moves with the gauge ring 41 to deflect the sealingring 14 radially outward in use. An O-ring 18 may be disposed along theinterior wall of the deflecting ring 12 that functions to achieve a sealbetween the deflecting ring 12 and the outer wall of the cylindricalmandrel 32.

The deflecting ring 12 can be made from any suitable material orcombination of materials including, but not limited to, PTFE (filled orvirgin), PPS, PEEK, elastomer, thermoplastic material or metal/alloy.The ‘upper’ and ‘lower’ back-up systems 16 can be made from any materialor combination of materials including, but not limited to, Sintermesh™,Unsintermesh™, steel mesh, wire mesh, graphoil with wire mesh, or thelike, with the back-up systems being capable of expanding to closeextrusion gaps between the gauge ring and the casing interior. As shown,the ‘upper’ and ‘lower’ back-ups each include Sintermesh™ 42 adjacentUnsintermesh™ 44. The ‘upper’ and ‘lower’ Sintermesh™ components 42 maybe asymmetrical and have modified shapes. For example, the angle of face46 of the deflecting ring 12 immediately adjacent to and facing in thedirection of ‘upper’ Unsintermesh™ component 44 may be 55 degrees,whereas the angle of face 48 of the sealing ring 14 immediately adjacentto and facing in the direction of ‘lower’ Unsintermesh™ component 44 maybe 35 degrees.

In comparison to the “single-ramp” arrangement shown in FIG. 1, sealingassembly 40 is a “double ramp” arrangement, resulting in a longer axialseal capable of withstanding higher pressures. Specifically, thedeflecting ring 12 is an annular ring defining first and second ramps50, 52 (i.e., at an angle to the axial direction) spaced by anintermediate flat 54 (i.e., parallel to the axial direction). The firstand second ramps 50, 52 face and slide in physical contact againstcorresponding ramps 56, 58 of the sealing ring 14, also spaced by a flat60. During setting, ramps 50 and 58, as well as ramps 52 and 56, slidepassed one another such that the thin-walled portion of the sealing ring14 is deflected radially outward of the thick-walled portion of thedeflecting ring 12, and the thin-walled portion of the deflecting ring12 is forced radially inward of the thick-walled portion of the sealingring 14, and wherein the respective portions overlap in the axialdirection. When set, the deflecting ring 12 and sealing ring 14 thuseffectively interlock based on their predetermined shapes. The largercross-section of the ‘overlapped’ deflecting ring 12 and sealing ring 14as compared to the gap between the mandrel and inner wall of the casingforms the seal.

The foregoing description provides embodiments of the invention by wayof example only. It is envisioned that other embodiments may performsimilar functions and/or achieve similar results. Any and all suchequivalent embodiments and examples are within the spirit and scope ofthe present invention and are intended to be covered by the appendedclaims.

What is claimed is:
 1. A sealing assembly for sealing an annulus in adownhole application, comprising: a sealing ring and a deflecting ringaxially aligned between axially opposed mesh back-ups, each of thesealing ring and the deflecting ring defining a first ramped end, thefirst ramped ends of the sealing ring and the deflecting ring arrangedfacing each other such that an axial set force applied to the deflectingring deflects the sealing ring radially outward forcing the sealing ringinto a side-by-side arrangement with the deflecting ring to fill andseal the annulus.
 2. The sealing assembly of claim 1, wherein thesealing ring is deformable such that when the sealing ring is forcedradially outward, the sealing ring extends axially and compressesradially.
 3. The sealing assembly of claim 1, wherein the sealing ringhas a larger cross-section before the axial set force is applied thanafter the axial set force is applied.
 4. The sealing assembly of claim1, wherein the deflecting ring defines a recess along the length thereoffor receiving a portion of the sealing ring therein when the sealingassembly is in an expanded configuration.
 5. The sealing assembly ofclaim 1, wherein each of the sealing ring and the deflecting ring definea second ramp spaced from their respective first ramped end, wherein thesecond ramp and the ramped end of each of the sealing ring and thedeflecting ring are parallel such that when the set force is applied,the first ramped end of the sealing ring slides against and passes thesecond ramp of the deflecting ring, and the first ramped end of thedeflecting ring slides against and passes the second ramp of the sealingring, in the axial direction.
 6. The sealing assembly of claim 1,wherein the sealing ring defines a second ramped end at a 35 degreeangle to the longitudinal axis of the sealing assembly, and thedeflecting ring defines a second ramped end at a 55 degree angle to thelongitudinal axis of the sealing assembly.
 7. The sealing assembly ofclaim 1, further comprising an o-ring retained against an inner wall ofthe deflecting ring.
 8. The sealing assembly of claim 1, wherein thedeflecting ring is constructed from one or more of PTFE, PPS, PEEK,elastomeric material, thermoplastic material, metal and metal alloy. 9.The sealing assembly of claim 1, wherein the mesh back-ups areconstructed from one or more of steel mesh, wire mesh, and graphoil withwire mesh.
 10. The sealing assembly of claim 1, wherein the sealing ringis constructed from one or more of elastomeric, thermoplastic andgraphitic materials.
 11. A sealing assembly for sealing an annulus in adownhole application, comprising: a sealing ring and a deflecting ringaxially aligned between axially spaced mesh back-ups, each of thesealing ring and the deflecting ring defining a first ramped end and asecond ramp spaced from the first ramped end, the sealing ring and thedeflecting ring arranged such that, when an axial set force is appliedto the deflecting ring, the first ramped end of the deflecting ringslides against and passes the second ramp of the sealing ring and thefirst ramped end of the sealing ring slides against and passes thesecond ramp of the deflecting ring to deflect the sealing ring radiallyoutward to force the sealing ring into an arrangement in which thesealing ring at least partially overlaps the deflecting ring to seal theannulus.
 12. The sealing assembly of claim 11, wherein the sealing ringfurther defines a second ramped end at a 35 degree angle to alongitudinal axis of the sealing assembly, and the deflecting ringdefines a second ramped end at a 55 degree angle to the longitudinalaxis of the sealing assembly.
 13. The sealing assembly of claim 11,further comprising an o-ring retained against an inner wall of thedeflecting ring.
 14. The sealing assembly of claim 11, wherein thespaced mesh back-ups comprise one or more of steel mesh, wire mesh, andgraphoil with wire mesh.
 15. A sealing assembly for sealing an annulusin a downhole application, comprising: a deformable sealing ring and arigid deflecting ring axially aligned between axially spaced meshback-ups, each of the deformable sealing ring and the rigid deflectingring defining a first ramped end, the first ramped ends of thedeformable sealing ring and the rigid deflecting ring arranged facingeach other such that an axial set force applied to the rigid deflectingring deflects the deformable sealing ring radially outward relative to alongitudinal axis of the sealing assembly, axially lengthens thedeformable sealing ring, and radially compresses the deformable sealingring to force the deformable sealing ring into a side-by-sidearrangement with the rigid deflecting ring to fill the annulus.
 16. Thesealing assembly of claim 15, wherein the deformable sealing ring has alarger cross-section before the axial set force is applied than afterthe axial set force is applied.
 17. The sealing assembly of claim 15,wherein the rigid deflecting ring defines a recess along the lengththereof for receiving a portion of the deformable sealing ring thereinwhen the sealing assembly is in an expanded configuration.
 18. Thesealing assembly of claim 15, further comprising an o-ring retainedagainst an inner wall of the rigid deflecting ring.
 19. The sealingassembly of claim 15, wherein the deflecting ring is constructed fromone or more of PTFE, PPS, PEEK, elastomeric material, thermoplasticmaterial, metal and metal alloy.
 20. The sealing assembly of claim 15,wherein the sealing ring is constructed from one or more of elastomeric,thermoplastic and graphitic materials.